1. Field of the Invention
The present invention relates to a semiconductor device, a method for manufacturing the semiconductor device, and an integrated circuit including the semiconductor device. More particularly, the present invention relates to a semiconductor device having a thin film resistor, a method for manufacturing the semiconductor device including a thin film resistor, and an integrated circuit including the semiconductor device including a thin film resistor.
2. Brief Description of Related Art
In manufacturing an integrated circuit, an active region including a transistor or a diode and a passive region including a resistor or a capacitor are generally formed on a semiconductor substrate before forming a wiring layer thereon.
As for the resistor, a metal thin film, made of NiCr (nickel chrome), TaN (tantalum nitride), CrSi2 (chromium silicide), CrSiN (chromium silicon nitride), CrSi (chromium silicon), or CrSiO (chrome silicon oxide), for example, is widely used for high feature resolution and circuit miniaturization.
FIG. 1D illustrates a section of a conventional semiconductor device 1 including a thin film resistor 5. The conventional semiconductor device 1 additionally includes a substrate 2, an underlying insulating film 3, and an interlaying insulating film 11. The thin film resistor 5 is usually manufactured in three main steps including photolithography (FIG. 1A), etching (FIG. 1B), and ashing (FIG. 1C).
The photolithography step of FIG. 1A deposits a photoresist 12 on a resistor material 4, and places a mask (not shown) over the surface of the photoresist 12 for pattern definition. Thus, after being exposed to radiation, such as ultraviolet light, only a selected area of the photoresist 12 remains as a photoresist pattern 13, as shown in FIG. 1B. Next, the etching step of FIG. 1B etches the resistor material 4 by using the photoresist pattern 13 as an etching mask to form the thin film resistor 5. The ashing step of FIG. 1C removes the photoresist mask 13. The interlayer insulating film 11 is then formed so as to protect the thin film resistor 5, and the manufacturing process ends.
Recently, in the ashing step of FIG. 1B, dry ashing, such as plasma ashing using plasma-containing oxygen, is preferably used. However, applying the oxygen plasma may form an oxide film on the surface of the thin film resistor 5, resulting in variation in the resistance value.